friction measurement on common floor using a horizontal ... · or a subjective approach. the former...
TRANSCRIPT
Abstract—Slips and falls are common incidences both at work
and during leisure activities. Lack of friction on the floor surface
has been blamed as the source of slips and falls. Friction of floor
is one of the dominate factors affecting the risk of slips and falls.
In general, a person is more likely to slip when walking on a
floor contaminated with water or soapy solution than the dry
surface. In this research, we conducted friction measurements
on twelve floor tiles. The three surface conditions of the floors
were dry, wet and soapy liquid contaminated conditions. The
horizontal pull slip meter (HPS) was used. The measured
coefficient of friction (COF) results showed that the HPS
reported the COF readings on the same floor differently. It was
found that floor tiles and surface condition were both
significant on the measured COF. The HPS model defined in this
study provides a mathematical description of the measured COF
under the studied floor and surface.
Index Terms—Slip and fall, risk of fall, friction, horizontal
slip meter.
I. INTRODUCTION
When a slip and fall accident occurs and is investigated,
one of the fundamental considerations is the slipperiness of
the walking surface where the slip occurred [1]. Friction of the
floors, or alternatively floor slipperiness is one of the critical
parameter in affecting the risk of slip and fall incidents which
are a major source of occupational injuries. There are a
variety of contexts of which slips, trips and falls may occur, it
is imperative to understand their greatest potential for danger
[2]. Many hazards associated with slip, trip and fall injuries
include floor cleaning, leaks, and incidents which occur
because of materials and debris left on walkways such as
protruding nails and boards, bunched floor mats, uneven
carpeting, holes or depressions in working surfaces, and
step-risers on stairs that are not uniform in height [2], [3].
The control of slipping events requires the establishment of a
friction standard for the shoe/floor combination and
enforcement of materials that meet this standard.
Friction between the shoe and the floor may be determined
statically or dynamically.
The former is the static coefficient of friction (SCOF) and
the latter is the dynamic coefficient of friction (DCOF). The
SCOF determines the initiation of a slip when a shoe sole is
impacting on the floor. The DCOF is expected to be
Manuscript received December 20, 2018; revised June 30, 2019. This
research was partially supported by a research funding of the Ministry of
Science and Technology of the Republic of China under grant
MOST106-2221-E-216-008-MY3.
Samsiya Khaday and Kai Way Li are with the Department of Industrial
Management, Chung Hua University, Hsin-Chu, Taiwan (e-mail:
determining factor affecting whether a slip once initiated will
continue or not [4], [5].
Floor slipperiness may be measured via either an objective
or a subjective approach. The former involves using a friction
measurement device to measure the coefficient of friction
(COF) at the footwear–floor interface. The latter involves
collecting subjective ratings of perceived floor slipperiness
from human subjects. Friction measurements provide more
reliable floor slipperiness data [6]. It is generally believed that
floor surfaces with a measured SCOF of 0.50 or higher
provide adequate traction and, therefore, are safe [1], [7].
Friction measurement was commonly performed to
measure the slipperiness on floors [8], [9] and provide more
reliable floor slipperiness data [6]. The general consensus is
that surface with a lower coefficient of friction (COF) are
more slippery then those with a higher COF [8]. The
monitoring and control of COF could reduce the risk of
slipping on the floor and provide a safer walking
environment.
The required COF (or RCOF) values are commonly
assessed in gait experiment concerning slipping and falling
because they quantify friction required during walking.
Reference [10] conducted a gait experiment on a ramp
covered with either non waxed vinyl composite tile or a
low-loop carpet. The floor conditions included dry, wet, and
soapy liquid contaminated. Three ramp angles were used: 0°,
10°, and 20°. Their results indicated that a larger ramp angle
resulted in a higher RCOF for downward walking. The
numbers of slip and fall events they recorded increased as the
difference between the RCOF and the friction at the
footwear–floor interface increased. They estimated the
probability of a slip and fall based on the difference of the
RCOF and dynamic friction at the footwear–floor interface.
The literature apparently supported the common belief that
slips and falls are more likely to occur on an inclined surface
[11].
One of the slip meters most commonly used to measure
friction in a field environment in the USA is the Brungraber
Mark II(BMII), which is driven by gravity and known as a
portable inclinable articulated strut slip tester (PIAST) [5],
[8], [12]-[21]. However, the readings of the BM II are
affected by the inclined angle of the measured surfaces due to
gravity. Such readings may, then, require adjustments to
reflect the actual COF values of the surfaces [11]. The
horizontal pull slipmeter (HPS) is another alternative. As
compared with the BMII, the HPS is easy to use. The
Objectives of this study were (i) to study the effects of floor
and surface condition of on the COF of floor tile, (ii) to study
the correlation between the floor profile parameters and the
COF measured.
Friction Measurement on Common Floor Using a
Horizontal Pull Slip Meter
Samsiya Khaday and Kai Way Li
International Journal of Environmental Science and Development, Vol. 10, No. 9, September 2019
275doi: 10.18178/ijesd.2019.10.9.1187
II. RESEARCHES METHODS
To accomplish the objectives of the study, factors and/or
conditions related to the friction measurements, including the
measurement device, surface conditioning, floor tiles, and
measurement procedures are discussed in this section.
A. Friction Measurement Devices
Submit your manuscript electronically for review. The
horizontal pull slip meter (S.C.S Forces), used in this study, is
a laboratory and field instrument designed instrument to
collect data about the slip resistant characteristics of floors
(See Fig. 1). It includes the drive motor/power pack assembly,
a load dial/sled slip meter assembly, a calibration hook and
sanding block, as well as test materials. The load dial/sled slip
meter assembly incorporates three footwear specimens as feet
to contact the surface upon which the tests will be conducted.
These specimens are easily replaceable, allowing evaluation
of any specific materials at any time. This slipmeter employs a
motor to generate a drag force to pull a weight unit attached
with three footwear samples. The HPS is primarily intended
for the measurement of static slip resistance: that is, the force
required to cause the weight unit in contact with the floor
begin to move. It features a peak hold mode which will
capture the maximum force value and display the maximum
COF until reset by the operator. Total weight of slip meter
without the power unit is 2700 ± (34) g. the speed of pulling is
3.5 (± 0.5) in/min [22]. The HPS is primarily intended for the
measurement of static slip resistance: that is, the force
required to cause the weight unit in contact with the floor
begin to move. It features a peak hold mode which will
capture the maximum force value and display the maximum
COF until reset by the operator. Total weight of slip meter.
Fig. 1. Horizontal pull slip meter.
B. Floor Tiles
Twelve floor tiles were tested in this study (See Table I).
All of floors were ceramic 44.5×89.3cm two floors simple
size, 32.2×60 cm six floors simple size, 14.5×29.8cm two
floors simple size and 9.7×20cm two floors simple size for
testing. Four positions measured of friction experimental of
each of floors were difference position tested. Each of floors
position has three test footwear pad contact points on a
surface using a horizontal pull slip meter (HPS). The COF of
floors were measured using a horizontal pull slip meter (HPS).
C. Surface Conditioning
Prior to measurement, we wiped the walkway surface panel
with a 3% ammonium hydroxide (NH4OH) solution and dry
with a clean cloth. We placed the walkway surface panel on a
study bench or table in such a way that the panel does not
move during testing. The floor specimens was sanded using a
No.60 grit abrasive paper to remove mole release agents and
cleaned the sliding surface. We re-sanded the floor specimens
using a NO. 400 abrasive paper and brushed to remove loose
surface particles [22].
TABLE I: KIND OF FLOOR TILE AND DATA
Code Kind of floor Ra
A01
2.15 μm
A02
4.16 μm
A03
5.93 μm
A04
6.51 μm
A05
7.35 μm
A06
7.65 μm
A07
7.77 μm
A08
8.89 μm
A09
20.32 μm
A10
27.16 μm
A11
27.48 μm
A12
30.41 μm
Prior to experiment, we marked four measurements spots
on the floor piece. Every spot had three test footwear pad
contact points. For dry measurement, we placed horizontal
pull slip meter on a surface at one of the positions marked. For
wet measurements, prior to the measurements we needed to
soak the tile for 24 hours if the tile was stone floor. For Soapy
measurement, we added two liter water in the 4.5-gallon
bucket and then put 30 ml detergent in the water and then
frothy.
D. Measurement Procedures
Prior to each measurement, we marked four positions on
the surface. Every position had three test footwear pad contact
International Journal of Environmental Science and Development, Vol. 10, No. 9, September 2019
276
points on a surface. For dry experimental, we placed
horizontal pull slip meter on a surface at position mark and
placed the slip meter power unit on the surface in front of the
slip meter. The dragging unit and the weight unit of the HPS
should be on the same level (See Fig. 1). We then align the
pulley on the power unit with the hook on the slip meter and
connected the string of the power unit pulley to the hook of
the slip meter. The string was parallel with the test surface and
in line with the pulley on the power unit. We then put the
switch that permits retention of maximum slip index
indication in the center position.
Fig. 2. Friction measurement by horizontal pull slipmeter.
We set the slip index meter on zero by rotating the rim of
the gage on the push-pull meter and pushed the maximum
recording switch toward the hook less end of the slip meter.
We held down the power unit to prevent its moving; then
depressed the switch. We switched off the power unit when
the slip meter began to move. We then recorded the reading
shown on the slip index gage. For wet measurement, we used
a small cup (10 ml) to measure water content and put three
cops of water (10 ml) at positions marked three test samples
on surface (See Fig. 3). Pure water in all the cups on the
surface and proceed experiment using a horizontal pull slip
meter (See Fig. 2).
Fig. 3. Applying water on the surface.
For Soapy measurement, we added water into the
4.5-gallon bucket and put 30 ml dish washing detergent in the
water and then frothy. A small cup (10 ml) was used to
measure soapy solution content. We put liquid soap in a cup
of 10 ml and prepared three cups. We placed these cups on
positions marked on the floor samples and poured the soapy
solution in all the cups on the surface (See Fig. 3) and proceed
experiment using the horizontal pull slip meter (See Fig. 2).
We repeated this procedure four times for each set of three
specimens and rotated the horizontal pull slip meter 90° after
each test.
E. Statistical Analyses
The friction measurements were conducted using a two
factor (12 floor tile ×3 surface) randomized experimental
design with three replications. A two-way analysis of variance
(ANOVA) was performed for the measured COF values. A
regression model may be used to describe and predict the
COF values at the floor surface [4], [9], [11]. The statistical
analysis was performed using the SAS 8.0 software.
III. RESULT
The ANOVA results for the COF readings were
summarized in Table II. The COF of floor (p<0.001) and
surface condition (p<0.0001) were statistically significant on
the COF of floor, Duncan’s multiple range test results were
performed to compare the difference of the floors.
Table III shows the Duncan’s multiple range test results.
On the floor, the COF of floor A03 (0.63) was
significantly(p<0.05) higher than those of floor A12 (0.59),
floor A07 (0.57), floor A05 (0.55), floor A06 (0.54), floor
A11 (0.53), floor A10 (0.52), floor A04 (0.50), floor A01
(0.48), floor A08 (0.43) and floor A02 (0.42), the COF of
A09 (0.61) was significantly (p<0.05) higher than those of
floor as floor A03, the COF of floor A12 (0.59) was
significantly (p<0.05) higher than those of floor A05 (0.55),
floor A06 (0.54), floor A11 (0.53), floor A010 (0.52), floor
A04 (0.50), floor A01 (0.48), floor A08 (0.43) and floor A02
(0.42), the COF of floor A07 was significantly (p<0.05)
higher than those of floor as floor A12, the COF of floor A05
(0.55) was significantly (p<0.05) higher than those of floor
A10 (0.52), floor A04 (0.50), floor A01 (0.48), floor A08
(0.43) and floor A02 (0.42), the COF of A06 (0.54) and floor
A11(0.52) was significantly (p<0.05) higher than those of
floor as floor A05, the COF of floor A10 (0.52) was
significantly (p<0.05) higher than those of floor A01 (0.48),
floor A08 (0.43) and floor A02 (0.42), the COF of floor A04
was significantly (p<0.05) higher than those of floor as floor
A10, the COF of A01 (0.48) was significantly (p<0.05) higher
than both of floor A008 (0.43) and floor A02 (0.42).
For the COF, some of reading of floor A01, floor A018,
floor A02, were lower than 0.5, a safety standard commonly
adopted in the USA [6], [23]. However the friction on the
floor may lower than what had been measured. It will be
slippery and easily to injury occurs.
TABLE II: ANOVA TABLES FOR COF FOR FLOOR TILES
Source df SS MS F p-value
Floor
Surface
Floor*Surface
Error
Corrected Total
11
2
22
828
863
3.25
5.59
0.53
4.02
13.58
0.30
2.79
0.02
0.01
0.00
58.21
550.10
4.77
52.73
0.00
<.0001
<.0001
<.0001
<.0001
0.000
TABLE III: DUNCAN’S MULTIPLE RANGE TEST RESULTS FOR COF OF FLOOR
Floor Mean
Duncan
Grouping
A03 0.63 A
A09 0.61 AB
A12 0.59 BC
A07 0.57 CD
A05 0.55 DE
A06 0.54 DEF
A11 0.53 EF
A10 0.52 FG
A04 0.50 G
A01 0.47 H
A08 0.43 I
A02 0.42 I
Table IV showed the Duncan’s multiple range test results
of surface. The COF of the dry surface (0.63) was
significantly (p<0.05) higher than the COF for both of wet
(0.53) and Soapy surface (0.43). The COF of the wet surface
(0.53) was significantly (p<0.05) higher than that of the soapy
International Journal of Environmental Science and Development, Vol. 10, No. 9, September 2019
277
surface (0.43). The soapy surface was lower than 0.5 a safety
standard commonly adopted in the USA [6], [23] and was
believed to be unsafe as far as slip & fall is concerned.
TABLE IV: DUNCAN’S MULTIPLE RANGE TEST RESULTS FOR COF OF
SURFACE
Surface Mean
Duncan
Grouping
Dry 0.63 A
Wet 0.53 B
Soapy 0.43 C
IV. DISCUSSION
The results from the current study indicated that the mean
values of the measured coefficient of friction results by
horizontal pull slip meter had experiment and randomization
accuracy. It is major to measure friction on several floor tiles
and use the average to represent friction on the floor tiles. In
general, lower COF values were recorded for floors with
soapy surface condition and wet surface condition. The COF
increased as dry surface condition and decreased as wet
surface condition and soapy surface condition. The reading
measured coefficient of friction on the same floor was
difference might be no problematic due to the face of some
position on the floor might be difference roughness. This test
method covers measurement of the static slip resistance of
footwear sole, heel, or related materials on walkway surface
in the laboratory and in the field [22].
The twelve floor tiles showed the result that dry surface
condition of floorA06 was significantly higher than those of
floors, for the wet surface condition and soapy surface
condition of floorA03 were significantly higher than those of
floors. For the floor of minimum mean value of the measured
coefficient of friction reported dry surface condition of
floorA02 were lower than those of floors, for the wet surface
condition and soapy surface condition of floorA08 were lower
than those of floors (see Fig. 4). The result showed that dry
surface condition were significantly higher than those of wet
surface and soapy surface and wet surface condition were
significantly higher than those of soapy surface condition (see
Fig. 5).
0
0.2
0.4
0.6
0.8
A01
A02
A03
A04
A05
A06
A07
A08
A09
A10
A11
A12
COF Dry Wet Soapy
Fig. 4. COF measurement results on the twelve floor tiles.
The results showed that COF values of floor slipperiness
were significant (p < 0.001) under different surface condition.
The soapy surface condition was ranked as the most slippery,
followed by the wet surface condition and finally the dry
surface condition for the COF measured using the HPS.
0
0.2
0.4
0.6
0.8
Dry Wet Soapy
COF
Fig. 5. COF measurement results of the surface.
V. CONCLUSION
This research conducted friction measurements on 12 floor
tiles. There are three surface conditions were dry, wet and
soapy under four positions experimental of each surface
condition. The results from this study provide correctness
factor a using HPS. It was found that COF measurement range
test results on floorA03 were highest. It was least risk of
slipperiness and COF measurement range test results on floor
A02 were least. It was most risk of slipperiness of all of floors.
COF measurement range test results of dry surface were least
slippery and COF measurement range test results on soapy
surface were most slippery. The measured COF using the
HPS decreased as wet surface condition and soapy surface
condition, and increased as dry surface condition. The HPS
data in this study provides objective basis of the friction of the
floor samples which are beneficial for slip/fall prevention.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
AUTHOR CONTRIBUTIONS
KWL developed the concept & frame work; SK prepared
and conducted the experiment, and analyzed the data; KWL &
SK prepared the manuscript. All authors have approved the
final version.
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Copyright © 2019 by the authors. This is an open access article distributed
under the Creative Commons Attribution License which permits unrestricted
use, distribution, and reproduction in any medium, provided the original
work is properly cited (CC BY 4.0).
Samsiya khaday is with the Department of industrial
management Chung Hua University Hsin-chu,
Taiwan. Her research interests are industrial
engineering.
Kai Way is with the Department of Industrial
Management Chung Hua University Hsin-Chu,
Taiwan. His research interests are ergonomics, slip &
falls, muscular fatigue. His publications include Li,
KW, Zhao, C, Peng L (2018), Subjective
Assessments of Floor Slipperiness Before and After
Walk under Two Lighting Conditions, International
Journal of Occupational Safety & Ergonomics 24,
294-302. A Li, KW, Huang, SY, Chiu, W (2017), Ground reaction force and
required friction during stair ascent and descent, Human Factors and
Ergonomics in Manufacturing & Service Industries, 27, 66-73.
International Journal of Environmental Science and Development, Vol. 10, No. 9, September 2019
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